Emergency fuel supply system



May 26, 1953 c. F. scHoRN EMERGENCY FUEL SUPPLY SYSTEM 4 sheets-shew 1 Filed May 15, 1948 .6528 nmw w ESE R. 5. O T 7 E m NSK I V 0 m w a Y B EN Mmk G 4 :SQ kkx,

May 26, 1953 c. F. scHoRN EMERGENCY FUEL SUPPLY SY$TEM 4 Sheets-Sheet 2 Filed May l5, 1948 INVENTOE' May 26, 1953 Flled May 15, 1948 May 26, 1953 c. F. scHoRN EMERGENCY FUEL SUPPLY SYSTEM 4 Sheets-Sheet 4 Filed May l5, 1948 INVENToR.

Patented May 26, 1953 EMERGENCY FUEL SUPPLY SYSTEM Carl F. Schorn, Detroit, Mich., assignor to George M. Holley and Earl Holley Application May 15, 1948, Serial No. 27,187

12 Claims. 1

The object of this invention is to provide an emergency pump and fuel control system for a Ygas turbine when the normal fuel control system fails to function correctly.

Specifically, the object is to bring in an emergency pump and control system whenever the normal system fails to maintain the speed up to the manually selected speed of the normal system and thereafter to maintain this speed with the emergency system.

An additional object is to operate the emergency pump at a low pressure when it is standing by for an emergency.

Fig. l shows diagrammatically the preferred form of the invention.

Fig. 2 shows an enlarged detail of the speed responsive means which controls the emergency system. v

Fig. 3 shows a simplied form of the invention. v

Fig. 4 shows a cross-section on plane 4-4 of Fig. 2.

Figs. 5, 6 and 7 show a modied form of the acceleration device.

Fig. 5 is a cross-sectional elevation taken on plane 5-5 of Fig. '7.

Fig. 6 is a partial cross-sectional plan View taken on plane 6-6 of Fig. 5.

Fig. 7 is a partial cross-sectional elevation taken on plane 'I--l of Fig. 5. i

In Fig. l, I is the fuel entrance. I2 is the normal fuel supply and control means, supplied through the pipe I4. I6 is the outlet from the normal control I2. I8 is the drive shaft driven by the gas turbine which drives the control I2 which contains a pump and a speed control. 20 is the lever which determines the speed of the normal control system I2. 22 is the link connected to the lever 28 which is also connected to the lever 24 and cam 26 which controls the emergency system, the subject of this invention. The lever 24 is connected to the link 28 which is connected to the lever 30 which controls the speed responsive device U through the cam 14.

In the position shown the device is operating on the normal fuel supply and control means I2. For this reason the normal escape pipe 32, connected to the passage 36, is closed by the selector valve 40 which is shown down. The emergency escape valve 38, which is integral with the lower portion of the valve 40, is shown open. This permits the emergency pump 42 to discharge freely through the passage 44, past the valve 38, past a check valve 46, to a passage 48 which connects to the fuel entrance I0.

The spring back of valve 46 is arranged so that the pump 42 will not overheat during the period it is standing by awaiting an emergency. The pressure, as determined by the valve 46, acts on the clearance around the under side of the selector valve 38--40 and provides the force which causes valve 38--40 to rise when the pressure above 40 is released.

A minimum pressure (less than 50 pounds per square inch) is maintained by the spring loaded valve 46.

The emergency system consists of the emergency pump 42 and the speed responsive element 50 which is shown in greater detail and to a larger scale in Fig. 2. 52 is the pilot valve controlling the iiow of operating fluid from the pas sage 44 to chamber 54. The chamber 54 communicates with the underside of annular piston 56. This piston 56 controls the Ipressure above the selector valve 40. The rise of piston 56 causes the low pressure in the chamber 60, which communicates with the passage 6I which is in free communication with the fuel entrance ID, to reduce the pressure pressing down on the valve 40 so that the valve 40 then rises.

When the normal fuel supply control means I2 is in operation the spring- 64 keeps the valve 58 on its seat. An electromagnetic element 66, controlled by an electric wire 68, operates to rise the valve 58 whenever the operator wishes to test the emergency system. This is one of two manual override controls of the speed responsive element 50. Lever and valve 91 is the other control which is opened whenever the operator wishes to substitute the normal system for the emergency system to be described later The pilot valve 52 is connected to a diaphragm l l0. The underside of the diaphragm I0 is in free communication with the fuel passage 44. The pressure in passage @al is maintained by check valve 4l. The chamber 12, above the diaphragm l0, communicates with the fuel entrance pressure in the passage 62 through the passages |54-I12 of the speed responsive element 50, as explained When describing Fig. 2. When operating with the normal fuel supply system I2 the pilot valve 52 is in the inoperative position in which it is shown which cuts off communication between the passage 44 and chamber 54 so that the valve 5B remains closed.

The cam 14, controlled by the lever 30, when rotated anti-clockwise compresses the spring '15, which spring engages with the upper side of the diaphragm 'I0 and tends to push the pilot valve 52 down into its operative position. This motion `force of the element |32.

is opposed by the pressure difference acting on the diaphragm lo which pressure difference is controlled by the speed responsive element 50 as hereinafter described.

A piston 80 is held against the cam 14 by a spring 82, A restriction 84 causes the pressure generated by a rapid upward movement of the piston 8D to momentarily move a piston valve 88 against the pressure exerted by aL spring 88. When the element il@ rises the low pressure passage 02 is put into communication with the pas:- sage 80. That is to say the pressure in the chamber 'i2 falls to the pressure in the fuel entrance I0. Thus during the rapid-,openingoi thenormal device I2, by the opening movement of the lever 38, the pilot valve 52 is inoperative despite the fact that the cam lll increases the pressure' on the spring "18 and thus tends to push the pilot.

valve 52 down into its operative position. This takes care of a too rapid movement by the pilot of the control linkage 20-22-24--28-38 An `eleu'lent |83 responsive to centrifugal force uncovers a port I8! and lowers the pressure in chamber |86 until the difference in pressure between the chamber |81?, and the pressure generated by the emergency pump 42 which acts through the screen |82 balances the centrifugal It is understood that an element |51 also responsive to centrifugal force has meanwhile moved radially under centrifugal action uncovering port |99 in passage |88 and compressing the relatively weak spring |58. This movement of the element |51 occurs at relatively low speed and places chamber 12 above diaphragm i3 in com iunication through passsage |12 with ll through a pas- |50 in the element I8? and through port 89 and a passage |88 to port HSI.

Emergency system- Operative Assume that the pilot valve 52 has descended because the speed of the turbine is not great enough to create pressure differences large enough to hold the valve 52 in the position shown.

This is due to the operation of the speed responsive element 5t, which will be described later. Under these circumstances the cam lll causes the spring It to push the pilot valve 52 down into its operative position. When that happens a sleeve Q2 moves up under the influence of the `fuel pressure .44 and as the pilot valve 52 moves down because the pilot valve 52 admits fuel under pressure from the emergency fuel pump 42 to the underside of the sleeve 92, This fuel under pressure acts on the piston 84 and opens the ball check valve 58.

The valve 40 rises under the influence of the emergency pressure acting on the bottom of valve 38. This pressure is transmitted through the clearance around the skirt of the valve 38. This pressure is assisted by a spring 4|. Valve 40 then opens the passage 38 permitting the fuel delivered from the normal fuel system I2 to escape below the valve 40, past the check valve 48, through the passage 48 to the fuel entrance I0.

Before the valve 38-48 rose fuel under pressure from the normal fuel supply I2 was admitted above the valve 40, along the passage 36, past a restriction 222 and a spring loaded check valve 223 to the upper side of valve 40. After the valve 38-40 has risen fuel under pressure from the emergency pump 42 is admitted through the restriction 220, past the spring loaded check` valve 22|, past lthe ball valve 58 (which is'now open) 4 into the chamber 8U, and along passage 6|. The moment the ball valve 58 is closed the fuel under pressure from the emergency pump 42 is thus available to reclose the valve 38-40 as pressure above the valve 40 builds up, immediately the valve 58 is closed.

Considering now the emergency operation of the gas turbine ,the valve 38 has risen and the fuel from emergency pump 42 canvr no longer es- 10 cape past the check valve 46. Under these circumstances the pressure rises to 300 or 400 pounds per square inch and the fuel flows to the fuel divider valve S4, controlled by the servo- Valve 95, which' controlled by the barometric element 9 8 inside the chamber |00. Chamber |00 communicates with a passage |02 and With the 'air' entrance to lthe air compressor of the gas turbine, not shown. At high altitude a large portion of the fuel is allowed to return to the low pressure pipe- |4 as the bellows 98 expands a'ndvalve tstravels to the left.

The flow divider valve $4 discharges a portion of the fuel toA ythe passage |04 through the venturi |08, past the control (governor speed responsive) valve |88, down the passage |I0, past the valve II2, along the passage ||4 to the gas turbine, not shown. In order that this supply of emergency fuel can take place the cam 16 has been manually rotated clockwise and a lever I IB has been rotated anti-clockwise compressing the spring ||8 which pushes the fuel control valve |08 to the left into the position which permits fuel to flow from the venturi |88, down the passage |I0, past the valve I|2 and out through the passage II4` The throat ofthe venturi |05 communicates with the chamber to the left of the diaphragm |22. Diaphragm |22 forms a wall of the lchamber |28 and engage with a spring |24, to the left of the diaphragm |22 and to the right of the washer |26, which Washer engages with the valve |08. The chamber |28, to the right of the diaphragmy |22, communicates through restriction |21 and also past a check valve |29 with the passage |38, which communicates with the passagedown stream of the venturi |08. A small restriction- 'maintains a slight ow throughI the chamber |20 lto the throat of the venturi |06 through't'he opening |23 and acts as a vent to chamber |28.

The valve |08 is engaged and controlled by the diaphragm |3'2L' The chamber |34, to the right of the diaphragm |32, communicates with a passage |36 and to the speed responsive element 50 as shown in Fig. 2. Chamber |38, t0 the left of the diaphragm |32, communicates with the outlet from the emergency fuel pump 42 past the underside of the diaphragm 10. The diaphragm |32 is therefore pushed to the right by the pressure differences controlled byfthe speed responsive element and is not influenced by acceleration. v

The diaphragm |22 is pushed to the left by the flow responsive pressures created by the venturi |00 and by the pressures imposed by the spring ||8 which is controlled'by the position of the linkage 22-28 and of the cam 2|y connected thereto, that is, by the manual control means. The flow through the venturi |06 creates a relatively low pressure in the 'chamber |20, which pressure is transmitted through the restriction |23. Diaphragm |22 thus responds to this low pressure as the right hand side of diaphrgam |22 is connected through passage |30' With'the downstream end of venturi |06'.

accessi When the earn 2B, first leaves the position in which it is shown in the drawing a cam lobe |40 moves to the left, a valve |42 is permitted to rise and the pressure above the valve H2 is reduced. to the pressure existing in the passage 3H which communicates through` the restriction |63 with the. chamber above the valve IIZ. Pipe 34 communicates with the pipe 32, which pipe isnovv at the low pressure existing in the fuel. entrance lo plus the slight pressure imposed by the checlcv valve eli., The valve U12 is, however, subjected on its lower face to the pressurecreated by the emergencyrfuel pump 62 asmodied by the valve |08. Valve H2 is thus pushed up into its openl position, that, is, the position it must assume during emergency operation tof permit luel to flow from passage llt: to passage` Mii A small amount of fuel` is bypassed around valve loll, that is, itis supplied direcoirom the passage illev through the adjustable restricted l opening teil, this being the idleadjustinent.

A cam lobe |21` engages with a lever lle mounted on the lever H6.` An adjustable cap screw Ill adjusts the relative position of the valve. |08 to the lever 2.4 at idle speeds. When the linkage is first, moved from the low speed position in which it is shown al roller H rides on. the cam lobe |2|1 and is carried bythe lever H9. A low speedadjustment device los isprofvided which isy normally held outv of action by a spring |01. During the ordinary operating condition cam lobe-26 engages' with the roller which is mounted directly on the lever H5.

The uel divider valve lillv suppliespart oi the fuel admitted from the .pump i12v to the passage IM and. discards a portion ofA the fuel` through the passage Mii, pastI the balanced cylindrical valve lds to thepipe ld. rlhe valve |48 is subjected on its left hand side to the pressure in passage it?. which is thepressure in the passage |34, plus a spring pressure. This spring pressure is adjusted by an adjustable plug |49.

A similar valvel It` is subjected on its left face to the pressure in the passage |634, and on its right face to the pressure in the passage lill, plus a spring pressure. rrhis spring pressure is adjusted by anl adjustable plug lill. When, the valveA |05 opens -fuel escapes downa pipe sato the low pressure pipe It. Y

The shaft 85, attached to the bellows et, is of such a sise that at highspeeds, Whenthepressures generated by the emergency pump l2 gives the equivalent of a false barometric readingy the servovalve de moves over tothe rightslightly so as to give a slightly richer mixture just before-the speed responsive diaphragm e d2 takes hold of the fuel throttle valve |63.

This is known as a` biasing eltectr 4andirnproves the regulation of speed. The absolute pressure acting on the shaftte is determined-by the restriction l-dil-Sl and the pipe 35 Ybalances the pressure on both ends of the valve t4.

The position of the valve Sil is regulated by the position of the barometric element 92E. The chamber ldd, enclosing the barometric element u8 is connected to theair entrance 'to the ysupercharger of the turbine, notshov/n, through a pipe H32;

Speed sensing element 50 (Figs. 2 cmd'd) In Fig. 2 lofi is the low pressure .passage connecting with the axial passage tot yof the governor mechanism 5e and with the low pressure in pas- 'sage e2; (See Fig. fl); Passage |56. has three branches |58., |66 'and lB2. Passage `|80 come 'municates with the liquid in chamber 5| surrounding of the element 5u, which chamber 5| at the pressure generated by the emergency pump 42.

rlhe mechanism inlFig. 21v isshown operating below the normali idlingspeed. 1n Fig. 1 a similar mechanism is shown operating above the idling speed'. Port itil is thus shown closed in Fig. l and is shown open in Fig. 2. In Fig. 2 port |55* comniunicates with the chamber Idil, to the left of the speed' responsive weight tot. The-spring |168 engages with the weight l to and pushes it to the right so as, to keep open the passage |58" leading to the chamber itil. The chamber l 6e eommuni- Cates through the passage Ill! to the axial passage |12 which communicates with the chamber "52; above the diaphragm willig. l). Under these conditions the centrifugal force acting on the weight il@ engages with the spring llt. This spring is ground to a delinite length and is made of a rate ofy stillness so that theA valve portion llt, of' the Weight llt, just closes the passage :t2 and also just closes the passage itt. Passage ite communicates with the liquid in the chamber 5l surrounding the governor mechanism 5t, that is to say with the liquid at the pressure of the fuel downstreamfrom the emergencypump and upstream from the check valve-dand Ill.

ri'he spring lit isdesigned purely to lend sta bility and has negligibleV effect on the pressure difierential acting on the two sidesofvv the weight |14. The right hand sidezof Weight |74 is in free communication through the opening |32 With the chamber 5i, that is, with the fuel" delivered from the pump 122. The moment the Weight moves the slightest distance to the right, away from its neutral position in which it is shown, the port iti-2 is opened and the port I8@ is closed. For this reason the pressure in the chamber |8121, to the left of` the Weight lli is controlled so that its value plus the centrifugal force of the Weight Ild just balances the fluid pressure admitted through the opening 82 plus a slight pressure from the spring llt. This pressure difference between the pressure in the chamber 5l andthe pressure in the chamber ltsv thus varies as the speed is squared. The pressure inthe chamber its is 'transmitted througha passage lee. to an axial passage ilil, through a restriction Idil..

As the speedincreases above idling the Weight H56 moves to the left compressing the spring itt until it isstopped by, the washer Edu. The port its is then closed so that new ceases along the passage il@ and the pressure inthe chamber 'loll becomes effective through the restriction |85, passage il? and so to the chamber l2. Thereafter the pilot valve responds to changes in speed, which changes in cause changes in the pressure in chamber i135, to lzeep valve V38 in equilibrium.

At extremely high, and dangerous speeds the Weight it@ pushes the Washer Brill to the left cornprjessing thespring teil. This movementuncovers the port Which communicates with the port ldd, which port is at 'the pressure delivered' by the emergency fuel pump 32 in the chamber El surrounding the element te. Thepressure ofthe fuel pump ft2 thus transmitted through the radial passage ilii, through the axialpassage` V12, vto the chamber' it. rlhis action decreases the pressure Vdifference on the diaphragm lll.- The spring lit then acts on-the pilot-valve 52 and causes the emergency system to `become operative as emergency fuel pump ,pressurefbecom'es effective inthe rcha'mbeiyll and` valve '58,is. opened.

7 Thus the system is placed in the emergency position.

Acceleration (Fig. 4)

The third passage |60 communicates through the passage |96, and with the radial passage |98 under the following circumstances.

A ilywheel 200 is provided with a slot 202 and is driven by the speed responsive element through a spring 204. When the flywheel 200 lags behind the speed responsive element during acceleration the slot 202 acts as a bridge to bring the passage |96 into communication with the passage |98. Lowspeed fuel pressure is thereupon transmitted through the passage |60, along the passage |95, through the slot 202, through the radial passage |99 and along the axial passage |12. Hence, the action of the pilot valve |52 in response to speed changes is delayed during the acceleration period.

The passage |36, referred to in the description of Fig. 1, communicates with the passage 206 which is a passage parallel to the axial passage |12. Passage 206 communicates with the chamber |04 through the passage |86, to thelright of the restriction |08.

The result oi this construction is that the pressure in chamber |34 in Fig. 1 responds to speed changes even during acceleration periods. However, the flow divider valve 94 is then operative to keep the fuel available for acceleration within safe limits at high altitudes.

Figure 3 A passage 2|0 communicates with chamber 12 and passage |12 below restriction |88, that means that during acceleration element 200 now controls pressure in chamber |34 as well as in chamber 12. This causes valve |08 to travel to the right to cut down the fuel received by the gas turbine during acceleration and to anticipate the action of the governor. This eliminates the need for the flow divider 94, etc., shown at the bottom of Fig. l. However, the altitude correction is sacrificed to the simplicity thus gained.

As before the emergency pump pressure acts through restriction 220, check valve 22|, to the topside of valve 38-40 and starts it on its way down. This interrupts llow from the normal escape pipe 322, past selector valve 40 and pressure from normal system l2 builds up and acts through restriction 222 and valve 223 to the top of valve 40 and completes the closure of the valve 40. This holds the spring surrounding valve -40 compressed cluring the normal operation of the systern.

Restrictions 220 and 222 are needed to make selector valves 38-40 return to position shown after valve 58 has risen, for any reason and has been returned to its seat.

In both Figs. l and 3 a manual override valve and lever 91 is shown. When this valve is opened by anti-clockwise rotation of the lever the sleeve 92 is returned by the spring above, to the stop below, that is to the position shown and the system is thus returned to its normal operating position, that is, to the position shown.

When electricity is manually allowed to ow by a switch (not shown) through the electromagnet 66 the valve 58 is opened and the emergency system is caused to take over. Assuming that the emergency system is satisfactory the return to normal is made by momentarily opening the manual override 98, this action forces down the sleeve 92 and closes the pilot valve 52. .The system immediately returns to the control of the normal system. The downward movement of the annular piston 92 is checked by a positive stop.

Normal control means The lever 20 of the normal control device |2 controls the speed of the prime mover (gas turbine) by varying the speed at which a centrifugal governor similar to 50 controls the flow of motive fluid. That is, the lever 20 corresponds to lever ||6 and engages with a spring corresponding to spring I8 to control a throttle valve corresponding to valve |08.

Acceleration (Alternative) In Figs. 5, 6, and '1 212 is a passage corresponding to |12 of Fig. 3. 298 and 299 are two passages corresponding to |98 of Fig. 3. 256 is a passage corresponding to |56 of Fig. 3. 212 is a passage corresponding to |12 of Fig. 3. 300 is a flywheel corresponding to 200 of Fig. 3. 304 is a spring corresponding to 204 of Fig. 3. 302 is a port corresponding to 202 of Fig. 3 in the valve 306. A bell crank lever 3|2 engages with a rod 308 on which is mounted the valve 306.

During a sudden (acceleration the Weight 300 lags behind (rotation being anticlockwise in Fig. 4). A bell crank lever 3I2 combined with the compression spring 304, mounted on the main body 350 of the speed responsive device, corresponds to the spring 204 of Fig. 3. The bell crank lever 302 engages with a piston valve 306 mounted on a rod 308 and is kept in engagement by the compression spring 304.

The valve 306 normally closes the communi cation between the two passages 256 and 212 but during acceleration the pin 308 in Fig. 7 moves to the left and thus places the two passages 256 and 212 in communication with each other.

Otherwise the operation of the speed responsive device shown in Figs. 5, 6, and '1 corresponds exactly to the device shown in Fig. 3. That is, when acceleration exceeds about 200 revolutions per minute per second the bell crank lever 302 rotates clockwise and the valve 306 allows the low pressure fluid in passage 256 to freely enter passage 212 which prevents the control valve 52 (Fig. 3) from descending during acceleration above this minimum figure.

What I claim is:

1. A fuel control system for a prime mover in which the speed of the prime mover is responsive directly to fuel flow, a prime mover speed responsive device including operative iuid under hydraulic diierential pressure, said device being adapted to increase the hydraulic pressure difference as the speed of the prime mover increases, an acceleration responsive device adapted to modify the increase in pressure by delaying the increase controlled by the speed responsive device during a rapid increase in speed of the prime mover, driving means for both devices from said prime mover, a normal fuel supply system including a first fuel supply pump driven by said prime mover and a rst manual control means, a rst escape outlet therefrom, an emergency fuel supply system including a second fuel supply pump also driven by said prime mover, a second escape outlet therefrom, a selector valve having two valve seats, one located in each escape outlet and designed so that as one opens the other closes, a pilot valve controlling the movement of said selector valve, a first moving wall controlling said pilot valve, a chamber on each side of said Wall, a passage from one chamber tothe hydraulic operating duid under pressure, a passage from the other chamber to the hydraulic pressure responsive to speed modied by acceleration 'so that the moving wall is moved by the pressure responsive to speed and acceleration, a first manually controlled variable spring pressure arranged to oppose the motion of said first moving Wall, a second moving Wall, a chamber on each side of said second moving Wall, a passage from one chamber to the hydraulic pressure responsive to speed, a passage from the other to the pressure generated by said emergency fuel pump to move said second wall in'response to speed changes, a second manually controlled variable spring pressure arranged to oppose the motion of said second moving wall, saidsecond manual control means being interconnected With the `first manual control means, two fuel outlet passages from the first pump and from the second pump leading to said prime mover, an emergency fuel throttle valve connected to said second moving Wall in said emergency fuel outlet passage, an emergency shut off valve in the end of said emergency fuel outlet passage, hydraulic means for holding the said shut off valve closed responsive to the pressure in the escape passage from said normal fuel supply system, hydraulic means for opening the emergency shut off valve responsive to the rise in pressure in said emergency fuel outlet passage When the selector valve moves to open the escape passage from the normal fuel supply system and to close the escape passage from the emergency fuel supply system.

2. A device as set forth in claim l in which there is a third escape passage from the emergency system, a balanced valve therein responsive to the pressure drop at said emergency fuel throttling valve, yieldable means opposing the opening of said balanced Valve.

3. A device as set forth in claim 1 in which there is a passage through which the acceleration responsive pressure is also applied to said second moving wall to modify the pressure responsive to speed so as to delay the motion of said Wall and the opening of said emergency fuel throttle.

4. A device as set forth in claim l in Which there is a fuel venturi in the said emergency fuel outlet passage, a third moving Wall responsive to the drop in pressure in said venturi, a yieldable connection from said third moving wall to said emergency fuel throttling valve, the motion of said third moving Wall in response to fuel flow to the prime mover being adapted to open said fuel throttling valve to improve the speed regulation of the prime mover.

5. A device as set forth in claim 1 in which there is a flow divider located in the emergency fuel passage, barometric means for moving said divider valve to reduce the ow to said prime mover at high altitude and to permit the balance of the fuel to escape.

6. A device as set forth in claim 1 in which there is a flow divider located in the emergency fuel passage, barometric means for moving said divider valve to reduce the flow to said prime mover at high altitudes and to permit the balance of the fuel to escape, a balanced valve controlling said escape, the pressure doWnsteam of said divider valve on the escape side tending to open said valve, the pressure downstream of said divider valve on the prime mover side tending to close said valve. yieldable means tending to close said valve.

10. 7. A device -as set forth in claim 1 in which there are low and high speed responsive means associated with the speed responsive means, said.-

loW speed means being adapted when starting and when running below idle speed to apply a minimum pressure to the low pressure side of said first moving Wall to prevent the pilot valve being moved during this-period and said high speed responsive means equalizing the pressure on both sides of said rst moving wall so that the yieldable means then moves the pilot valve into the position in which it operates the selector valve when a predetermined critical speed of the prime mover is exceeded.

8. The combination with a prime mover of the type in which the flow of motive fluid fuel controls the speed of the prime mover, a normal fuel supply pump, a normal passage for the flow of saidmotive yfluid fuel, pump and speed responsive control means for said motive fluid fuel, a rst manual control therefor, a first escape passage for the normal uid fuel on the pressure side of said normal fuel pump, a first fuel shut off valve in said escape passage, an emergency pump for supplying emergency motive fluid; when the normal supply and regulating means fails to maintain the speed of the prime mover above the selected speed and below the critical high speed, an emergency fluid fuel passage and a second escape passage therefrom on the pressure side of saidl pump, a second shut off valve in said second escape passage, an emergency speed responsive control valve for said emergency motive fluid fuel and a second manual control therefor to vary the speed to which the valve responds, and connected to the first manual control means, a governing system for said cutoff valves, comprising means driven by said prime mover providing a fluid pressure difference varying as the square of the speed of said yprime mover, means for closing the escape shut off 'valve of the emergency pump and simultaneously opening the escape shut off valve of the normally operated fluid fuel pump when the normal control means fails to maintain the speed of the prime mover up to the selected speed and also when the normal control means fails to maintain the speed of the prime mover below a predetermined high critical speed.

9. A device as set forth in claim 8 in which there is a second escape passage upstream from said emergency speed responsive control valve, a divider valve therein, barometric means controlling the position of said divider valve to reduce the flow towards said emergency speed responsive control valve at high altitudes.

10. A device as set forth in claim 8 in which there is a second escape passage upstream from said emergency speed responsive control valve, a second valve therein, spring loaded means moving said escape valve toward its closed position, means responsive to the pressure drop at said control valve to open said balanced valve against said spring loading means.

1l. The combination with a prime mover having a normal speed responsive means driven by said prime mover for admitting normal motive fluid fuel thereto under pressure and also for regulating the flow of said fluid fuel, manual means for varying the speed at which the normal speed responsive means controls the flow of normal fluid fuel to said prime mover, a first escape passage and valve therein for releasing the pressurel of said normal motive fluid fuel, an emergency speed responsive means driven by il said prime mover for substituting emergency motive fluid fuel for normal motive fluid thereto under pressure and also for `regulating the ow of said emergency fluid fuel, second manual means interconnected with first manual means for varying the speed at which the speed responsive means controls the flow of the einergency fluid fuel, a second escape valve for releasing the pressure of said emergency motive fluid fuel, a hydraulic governor for said first and second escape Valve, comprising means for developing a Variable uid pressure varying as the square of the speed of said prime mover, a pilot valve, means for moving said pilot valve said pilot valve to open said first escape valve and to close said second escape valve Whenever the normm regulation' means rails to maintain the speed of the 'prime mover up to the speed se1ected by said manual means.

12. A device as set forth in claim l1 which there is also an acceleration responsive device comprising a rotating ywheel driven by the hydraulic governor', a spring interposed between flywheel and governor, a valve moved by the relative 'motion between the hydraulic governor and the rotating ywheel, said valve being adaptedto release the pressure difference created by' the hydraulic governor when the acceleration exceeds 100 revolutions per minute per, second. CARL F. SCHORN.

No 'references' cited. 

